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UNITED STATES PATENT ()FFICEQ HERMANN HOWALDT, or nrnrnicusnonr, NEARKIEL, PRUssIA, GERMANY.

BALANCED SLIDE-VALVE.

a'PECIFIGATION forming part of Letters Patent No. 301,990, dated Jul 15,1884.

- Application filed February 3, 1984. (No model.)

To all whom it new concern.-

Be it known. that I, HERMANN HOWALDT, of Dietrichsdorf, near Kiel, inthe Kingdom of Prussia, German Empire, have invented certain new anduseful Improvements in Balanced Slide-Valves for Steam-Engines; and I dohereby declare that the following is a full description thereof.

The object of the invention is to reduce by the peculiar construction ofthe slide-val ve for sider the best means of carrying out the invention.

The accompanying drawings form a part of this specification.

Figure l is a section through one of the valves and the adjacentportions. Fig. 2 is a section at right angles to Fig. 1.

- with the steam'chest cover removed. The two figures embraced in 3 arehorizontal sections showing two arrangements of devices for holding thevalve in position laterally. Fig. 4 is a horizontal section through thevalve and the adjacent parts which discharge the steam from a firstcylinder into a second in a compound .engine. Fig. 5 is a correspondingcross-section. Fig. 6 is a cross-section'showing a modification.

Similar letters of reference indicate corresponding parts in all thefigures where they occur. 1

Figs. 1, 2, 3, and 3 represent a slide-valve, a, of the D-slide type ofa steam-engine with one cylinder. This slide-valve a forms a prismaticbody of rectangular cross-section, provided with the passage necessaryfor the steam, and which is worked by valve-gear (not'shown) to slide upand down or fore and aft, as the case maybe, upon the valve-face of thecylinder 0 and the inner face of the lid D of the steam-chest.

Supposing the face d of the slide-valve a to Fig. 3'is a' top view ofthe valve and the adjacent parts small pressure, with the tendency tolift the I 1 be uninterrupted and full, the fresh steam could not pressat all upon the slide-valve a, while the under side a would endure onlya slide-valvea from the face of the cylinder 0.

To counterbalance this pressure recesses extending lengthwise on theupper face, d,-of the slide-valve a and of proportionate width areprovided, as shown in Figs. 1 and 2, adapted to allow the fresh steam toact upon this portion of the upper face, d. The same effect is attainedby providing a communication between the exhaust-pipe or the condenserof the engines and an excavation on the upper face, d, of theslide-valve a. (See Fig. 1.)

To prevent the slide-valve a from being forced by the steam-pressureupon the broader side 7 too tightly between the convergent faces of thelid D and the cylinder-face C, it is set by an adjustable plate orstrip, f, extending along its narrow side 9 in such a manto prevent thesteam from entering between the working-faces. For greater security andfor steadying the slide-valv a, an adj ustable strip or plate, f,similar to that above mentioned, is arran gedworkin g against thebroader side h.

The adjustment of each set plate or strip f may be effected with somesuccess by screws,

as represented on the right-hand side of Fig.

3; but I have devised a preferable construction in which the end isbetter attained by wedges f, manipulated by screws and nuts, asrepresentedon the left-hand side of Fig. 3, on top of Fig 2, and in Fig.3. The wear of the working-faces g 7b of the slide-valve a and of theplates f is. compensated by readjusting the wedges f. A screw-stud, m,is fitted tightly and permanently in each end of the wedge f, (see Fig.3,)extendingl0osely through ahole in the end of the steam-chest,andserves thenceforward as a part off. M is a washer having its inner faceaccurately finished-and fitted steam tight against the correspondingsurface of the steam-chest. M is a nut fitted tightly on the stud m. Thesame construction being at each end, and the nuts being screwed uptightly,

hold the wedges f. firmly and make steam 'When it is desired to shiftthe wedge f, the nut M at one end is slackened,

tight joints.

. nor that it works freely and with the minimum 7 "of friction, at thesame time tightly enoughand the corresponding nut at the opposile end ofthe steam-chest is tightened.

In Figs. 4 and 5 are shown parts of the two cylinders of a compoundengine with the new trapezoidal slide-valve a arranged between theslide-faces of the cylinders I and II, which faces are parallel in axialdirection, but inclined or converging in the other, correspond ing tothe converging faces of the slide-valve a. (See Fig. 5.) The steam-chestbelongs jointly to both cylinders I and II. The slidevalve a is set byan adjustable strip or plate, f, working against the narrower side 7 ofthe slide-valve a. A collateral strip, 1, is provided against thebroader side 71. The crosssections of the wedges, by means of which theset-platesf are adjusted, are indicated by f This form, which I willterm the new trapezoidal slide-valve, is important for twineylinders ofcommon \Voolt' or compound or other engines, as it works steanrtightupon the slide-faces of each of the two cylinders, and at the same timewith the minimum of friction and capacity for perfect adjustment. \Vherea second slide, a, for the cut-off is used on top of the slidevalve afor the distribution and expansive working of the steam, one of them maybe of rectangular cross-section and the other of trapezoidal section, inwhich case the working-faces 0f the chestlid and of the cylinder, orthose of two cylinders, should be converging; or the cross-section ofboth slide-valves a, and amay be a trapezoid, in which case thesteam-chest is- After having described my invention and suitable meansto carry it into effect, I clai1n The adjusting-stiuls m, steam-tightwashers M, and nuts M, in combination with the adj usting-wed ge f andguidingstripf,arranged to serve relatively to each other and totheslide-valve a of a steam-engine.

This specification signed by me this 21st day of December, 1883.

HERMANN HOWALDT. Vitnesses:

CLARUS KonNnoLi), Enxs'r BRUGKELMANN.

